textproduct: Rapid City

KEY MESSAGES

- A few severe thunderstorms are possible this afternoon especially across south central SD; damaging winds and large hail could occur.

- Hot temperatures will return for the second half of the week, with above average temperatures. This will result in near- critical fire weather conditions.

DISCUSSION

(This Evening Through Tuesday) Issued at 142 PM MDT Tue Sep 1 2026

Water vapor imagery shows a strong upper wave lifting NE, crossing the Dakotas/eastern MT. Surface analysis shows a surface low across north-central WY. Low level SE flow is drawing increased moisture across central SD, wrapping backwards towards the plains east and north of the Black Hills. Dewpoints are varying widely...from the 40s across parts of NE WY to the 50s over far western SD to around 70 over far SCentral SD. A dryline boundary south of the surface low is expected to slide eastward across SW SD/Neb panhandle late this afternoon and evening. This low level forcing will combine with an upper wave, supporting thunderstorm development. The best instability will be ahead of the dryline across SCentral SD, with MLCAPE reaching 2500 J/kg. Shear is decent enough for supercells, with large hail and damaging winds. Farther west across the SD plains where higher Theta E air has drawn in: some isolated thunderstorms are possible, but not enough instability for severe weather. Severe storms will exit the eastern border of the CWA by mid-evening but could see lingering showers over NE WY/NW SD lingering for a few more hours. Then low amplitude ridging sets up across the region overnight into Wednesday morning, resulting in strong warm air advection. Sunny skies will return and temperatures are expected to top out in the mid 90s across portions of the western SD plains. Temperatures well above average will continue through the end of the week...which could be in the upper 90s Fri/Sat. While isolated thunderstorms can't be ruled out most days, the pattern will be generally dry for the second half of the week.

AVIATION

(For the 18Z TAFS Through 18Z Wednesday) Issued At 1112 AM MDT Tue Sep 1 2026

Current widespread showers are continuing north and east across the area. Minor instability will support another round of precip in northeast WY later this afternoon (22Z). Growing instability will support storms across western and southern SD, with an emphasis on stronger storms possible in south-central SD. Stronger cores may cause IFR/MVFR conditions due to heavy rain and lower ceilings, along with gusty and erratic winds. Wednesday morning, MVFR/IFR ceilings are possible east of the Black Hills breaking up later in the morning.

FIRE WEATHER

Issued At 142 PM MDT Tue Sep 1 2026

Hot and dry weather returns Wednesday through the end of the week with near-critical fire weather conditions expected. Relative humidity may bottom out at 10 to 15 percent on Thursday and Friday across northeastern WY and far southwestern SD. If the likelihood of windy conditions increase, then critical fire weather conditions will be possible. Will continue to monitor.

UNR WATCHES/WARNINGS/ADVISORIES

SD...None. WY...None.